so, the thing that strikes me here is that in my earlier treatments of correlated noise fields I did not uinclude the `galsim.Pixel` - I treated the noise as being on the bvalues of samples.  this does change how the correlated noise object will look after a convolution with another kernel.

I think you're right that here it ought to be a `galsim.Pixel`... but I do remember that using the `Nearest` interpolator on the `InterpolatedImage` used to store the CF in the `CorrelatedNoise` class gave pretty bad results (`Linear` ended up working better). I'm not sure how best to reconcile the difference, I need to thnik